Circuit breaker mounting and connecting stud



Dec. 10, 1946. H. c. GRAVES, JR

CIRCUIT BREAKER MOUNTING AND CONNECTING STUD Filed Aug. 25, 1942 5 Sheets-Sheet 1 INVENTOR. flmiezkr C kqvzg Jet Dec. 10, 1946.

CIRCUIT H. C. GRAVES, JR

Filed Aug. 25, 1942 BREAKER MOUNTING AND CONNECTING STUD 5 Sheets-Sheet 3 INVENTOR.

6 5/9552? 6. 624mm, di

Dec. 10, 1946. H. c. GRAVES, JR 2,412,259

CIRCUIT BREAKER MOUNTING AND CONNECTING STUD Filed Aug. 25, 1942 5 Sheets-Sheet 4 INVENTOR. .zlg L2 MWEAWT C den 5,119.

A BY

Dec. 10, 1946. H. c. GRAVES, JR 2,412,259

CIRCUIT BREAKER MOUNTING AND CONNECTING STUD Filed Aug. 25, 1942 5 Sheets-Sheet 5 %WM6 3W Patented Dec. 10, 1946 CIRCUIT BREAKER MOUNTING AND CONNECTING STUD Herbert G. Graves, Jr., West Chester, Pa., assignor to I. T. E. Circuit Breaker Company, Philadelphia, Pa., a corporation of Pennsylvania Application August 25, 1942, Serial No. 455,978

1 Claim. 1

My invention relates to circuit interrupters and more particularly to a mounting means for supporting the same upon a switch board in a readily accessible and demountable manner.

The smaller types of circuit breakers are usually fully enclosed in housings of phenolic insulation which are so arranged as to cooperate with various types of mounting means for securement on switch boards.

Such frames or casings of phenolic material are rather stiff and inflexible and cannot ordinarily be manufactured to minutely accurate dimensions. It often occurs therefore that the rear face of the molding which rests against the panel of the switch board or which is supported by the various mounting means within the switch board is not a perfect plane.

Owing to the nature of the material, the openings in the moldings for the passage of mounting studs are not necessarily always in perfect alignment. Accordingly, the tightening of all supporting members when such a circuit breaker is mounted in the switch board may at times apply stresses to the molding which may tend to deform or break the same and thus interfere with the proper function of the interrupter.

My invention provides special mounting means which may readily be adjusted to securely position a circuit interrupter in such a casing on a frame without applying such bending or deforming stresses thereto where any misalignment or irregularity occurs.

My invention also contemplates the formation of a mounting stud and the arrangement thereof in such a manner that all of the parts thereof that must be manipulated to secure and detach the circuit breaker on the panel will be accessible from the front.

Accordingly, it is an object of my invention to provide novel means for mounting a circuit interrupter upon a switch board or panel which permits the removal of the circuit breaker for inspection or repair without requiring access to the circuit connections at the rear of the panel.

Another object of my invention is to provide mounting means for a circuit interrupter which, in addition, serve as the electrical conductors for connecting the circuit breaker terminals to the power and load terminals.

Another object of my invention is to provide circuit breaker mounting means comprising a plurality of studs having the load or line connections thereon and which are rigidly mounted upon a panel.

A further object of my invention is to provide 2 means for mounting a circuit interrupter upon a panel board so that the removal of the circuit interrupter will not in any way affect the electrical connections of the line and load terminals.

A still further object of my invention is to provide a stud rigidly and non-rotatably supported upon a panel to which the circuit breaker may be mechanically and electrically connected.

Another and primary object of my invention is the formation of a mounting stud having adjustable members which will permit the stud to accommodate itself to planar variations in the molding of the circuit breaker housing or to any misalignment of the openings therein.

Still another and corollary object of my invention is the formation of a mounting stud for a circuit breaker in such a manner that the effective length of the stud for securing purposes may be varied by the insertion or replacement of adjusting members.

These and other objects of my invention will now be apparent in the following specification and drawings, in which:

Figure 1 is a side View of a circuit breaker and supporting panel showing two species of circuit breaker mounting means in section.

Figure 2 is an end sectional view of the multipole circuit breaker illustrated in Figure 1 taken along the line 2-2 and showing the two different species of Figure 1.

Figure 3 is an exploded view in perspective of the circuit breaker mounting means.

Figure 4 is a fragmentary cross sectional view of a modification of the two circuit breaker mounting means shown in Figure 2.

Figure 5 is an exploded perspective view of the apparatus illustrated at the left in Figure 4.

Figure 6 is a cross-sectional view corresponding to that of Figure 4 but showing a slightly different form of mounting means.

Figure '7 is an exploded view in perspective view of the mounting stud shown at the left in Figure 6 showing a construction wherein an additional floating element is provided which serves to prevent rotation of the stud.

Figure 8 is a cross-sectional view corresponding to those of Figures 4 and 6 showing, however, a slightly modified stud.

Figure 9 is an exploded view in perspective showing the modified mounting stud to the left 'end in Figure 8.

Figure 10 is a cross-sectional view corresponding to those of Figures 4 and 6 showing, however, a slightly modified mounting means.

Figure 11 is an exploded view in perspective the mounting stud shown at the left in Figure 12 showing a construction wherein an additional floating element is provided which serves to prevent rotation of the stud.

Figure 14 is a cross-sectional view corresponding to those of Figures 4 and 6 showing, however, a slightly modified stud.

Figure 15 is an exploded view in perspective of the mounting stud shown at the left in Figure 14 showing a construction wherein an additional floating element is provided which serves to prevent rotation of the stud.

Figure 16 is a cross-sectional view corresponding 'to those of Figures 4 and 6 showing, however, a slightly modified stud,

Figure l? isan exploded view in perspective of the mounting stud shown in Figure 16 showing a construction wherein an additional floating element is provided which serves to prevent rotation of the stud.

Figure 18 is a cross sectional view corresponding to the upper left hand stud assembly of Figure 1, but showing the use of a floating metal insert.

A typical panel board arrangement for small manually operable circuit breakers is illustrated in Figures 1 and 2 and comprises essentially a circuit breaker base I I which contains the operative members of the circuit breaker mechanism and an enclosing cover it which is secured against the base H to form the completed unit,

The circuit breaker illustrated is a multi-pole unit the number of poles being dependent upon the particular application. This circuit breaker forms no part of the present invention and may, of course, comprise any unit which may be mounted upon the means to be described. The circuit breaker illustrated is contained within the body members I i and !2 of phenolic insulation or the like.

A panel l3 provides the front face of the switch board and is perforated-at Hi to permit the manual operating lever l5-to extend through. Any number of circuit breakers may of course be mounted beside each other to form the required panel board.

As illustrated in Figure'2, the panel board is built up between the two side panels l6 and I? which are maintained in spaced relation by a plurality of insulating plates secured to the rear flanges thereof, by a suitable number of bolts 22 which pass through perforations in the channel flanges and in the insulating panels, and are secured by nuts 23.

As'illustrated in Figure 1, the rear bracing of I engage in nuts 25 whichare secured as by welding to the flanges of the channels. Each pole of the electrical circuit interrupter illustrated in Figures 1 and 2 is provided with a pair of terminals 26 and 21 which are electrically connected to the conductors 5i and 32 of the power and load circuits.

Thus a single pole of the circuit breaker is arranged to electrically connect terminals 23-21 when its operating contacts are in the closed position.

The electrical connection between the terminals 25 and 2? and their respective bus bars 3| and 32 is made through studs 33 and 34 which in addition serve to provide the necessary mechanical support for the circuit interrupter. Thus, as will be described, the studs 33 and 34 are non-rotatably positioned upon the insulating panels 2! or 2211 and Zib and are spaced so that the circuit interrupters may be positioned thereon as illustrated and so that electrical contact between the line terminals 26 and 2? may be established therewith.

The various components of a single stud connection are best illustrated in Figure 3 which has been exploded to show the necessary relationships. Thus the stud connection 33 of Figure 1 comprises essentially a metallic cylindrical member 35 which is milled to form the flat surfaces 36 thereupon. The milling of these flat surfaces forms a shoulder 31 on each side of the stud.

The section ll of the cylindrical member has been reduced in diameter and threaded up to the shoulder 32 formed by this reduced diameter section. At the opposite end of the cylindrical member, a reduced diameter section 43 is threaded and provides a shoulder i l. As illustrated in Figures 1 and 2, when the circuit interrupter is mounted upon the studs, the reduced diameter threaded section "53 extends through the body of phenolic insulation '35 and through a metallic insert 45 which has been molded into the main body of the circuit breaker.

The section 43 also extends through a perforation ll in the line terminal 25 and good electrical and mechanical contact is secured at the line terminal by tightening nut 5! against the line terminal and looking it by the use of a second nut (see also Figure 3).

The metallic insert 46 (Figures 1 and 2) extends beyond the phenolic insulation into which it is embedded and accordingly the shoulder M bears against one surface of the metallic insert and the line terminal 28 bears against the opposite surface. Hence the tightening of the nuts 5! and 52 will impose stresses which are carried entirely by the metallic member 25 and impose no material forces upon the weaker phenolic insulation of the circuit breaker body.

The member 45 is provided with a circular rib it which precludes relative motion between the metallic insert and its associated framework of insulation.

The stud 33 is rigidly and non-rotatably supported upon the insulating panel 2i within a perforation 53 (see particularly Figure 3) which has been counterbored at 54 at one end and 55 at the other end thereof,

The internal angular flange 56 thus formed between the counterbores 54 and 55 has been drilled through at 51 and GI. In the mounting of the stud upon the panel 2i a washer 62 is first slipped over the cylindrical threaded portion ii.

This washer 62 has a central opening 63 which corresponds with the cross-section of the milled portion of the stud and accordingly the washer '5 62 may be non-rotatably positioned against the shoulder 31.

A second washer 64 having a central opening 65 corresponding to the opening 63 in washer 62 is also slipped over the threaded end H and positioned upon the flats 35 against washer 62. The washer 64 is preferably a stamping which contains a pair of oppositely disposed extensions 66 which are positioned to engage in the perforations 51 and 8| in the flange 55 in the insulating plate 2|.

Accordingly, when the cylindrical stud 33 is fitted with the washers 53 and 64 and passed through the perforation 53 so that the extensions 66 enter into their corresponding perforations, it may be seen that rotation of the stud will be impossible. The stud is then fixed to the panel 2| by slipping a washer 67 over the threaded end 4| so that it bears against the inner annular surface of flange 56 within counterbore 55 as illustrated in Figures 1 and 2 and the nut 1| is tightened against the washer 61.

It may be seen from Figures 1 and 2 that the axial length of the milled flats 36 is somewhat less than the sum of the thicknesses of the washers 62 and 6:3 and of the annular internal rib or flange 55 of the insulating plate 2|.

Accordingly, as may be seen from Figures 1 and 2, when the nut H is tightened against washer 61, the washer will bear against the annular I flange 56 within the counterbore 55 and the washer 64 will bear against the opposite surface of the flange 56 within the counterbore a. This engagement is then locked by the use of a lock nut 12.

Accordingly, when this assembly is complete, the stud 33 is rigidly and non-rotatably supported upon the insulating panel 2|.

The bus bar 3| may be connected to the threaded extension 4| of the stud by first positioning 1 a nut 13 upon the stud as illustrated in Figures 1 and 2, and passing the bus bar 3| over the stud through perforation i4 and locking the bus bar by means of a second nut l5. I

The tightening of nut 15 will provide good electrical contact between the bus bar and the stud. Since the stud is non-rotatably supported within the panel 2| it may be seen that the operations accompanying the removal of nuts 52 and 5| will in no way tend to loosen the nuts 13 and 15.

It therefore becomes possible to remove the circuit breaker from its mounted position illustrated in Figures 1 and 2 by first removing the front metallic panel l3 and employing a socket wrench to remove the nuts 52 and 5|.

Similarly, the breaker may be replaced by simply slipping the openings in metallic insets AS thereof over the threaded extensions 43 of the stud and securing the nuts 5| and 52. This operation will again have no effect upon the electrical connections of the bus bar 3| since the stud is non-rotatably supported.

As previously mentioned, it is quite possible that commercial phenolic moldings such as that employed upon the circuit breaker illustrated, may not have perfectly true surfaces. It has been found advisable, particularly in three-pole circuit interrupters to secure the base against the panel board in certain positions, that is, at certain stud locations and to prevent any clamping tress being imposed at other stud locations since it has been found that tight clamping at all stud locations would cause a warp in the molding which in turn would preclude proper opera- 6 tion of the circuit breaker or crack the phenolic casing thereof.

My mounting means therefore permits axial movement of one or more of the studs with respect to panel 2| in order that uneven or distorting clamping stresses may not be imposed upon the circuit breaker body. As an example, the stud 34 of Figure 1 and the stud 8| of Figure 2 have been shown with this type of connection.

In each of these illustrations, the washers 62 and El have been omitted and a bushing 82 having an outside diameter equal to that of the cylindrical portion 35 has been placed between the nut H and the shoulder 42 of the cylindrical portion 35. Otherwise the elements of the stud connection remain the same as illustrated in Figure 3.

The axial length of the bushing 82 is sufficient so that its outer annular surface extends beyond the surface of the annular flange 55 within the counterbore 55. Hence it may be seen that when the nut H is tightened, it is brought to bear against the bushing 82 which accordingly is forced against the shoulder 42. Hence there is no clamping action against the insulating panel 2| as a result of the tightening of the nut H and since, as illustrated in Figures 1 and 2, there is a clearance between the nut H and the surface of the flange 56 or between the washer 64 and the shoulder 3'! or between both these sets of elements, depending upon the position of the stud axial movement of the stud is possible.

But since the extensions 55 of the washer 54 are longer than the clearance provided for this washer, no rotation of the stud is possible.

Accordingly, this construction permits the clamping of the line terminal such as 21 to the stud 34 since as previously mentioned the clamping of the line terminal does not impose any stress upon the body of phenolic insulation.

A modification of my circuit breaker mounting is shown in Figures 4 and. 5 for mounting a circuit breaker on a metallic panel.

It is, of course, necessary when utilizing steel panels at the rear of a circuit interrupter to ensure that each of the studs which provides electrical and mechanical supporting means are insulated from the steel panel in order that the individual circuits may be isolated.

Referring to Figures 4 and 5, a portion of the circuit breaker terminal is illustrated and includes th insulating body H and the line terminal 3|. The stud comprises in this modification a circular flan e 26 having on one side thereof an integral threaded extension 9| of re duced diameter. At the other side of the flange an integral reduced diameter section 92 is knurled up to the edge 53 and threaded at 94 to the end of the studs. The stud 85 contains a cylindrical layer of insulation 95 molded directly thereupon, the knurling providing a rigid bond between insulation and metal.

The insulation is milled to provide a pair of opposed flats 95 extending from the main cylindrical section 95.

The insulation terminates in the shoulder 83.

As illustrated in Figure 4, the circuit breaker is connected to the stud in a manner similar to that in Figures 1 and 2. Thus the threaded extension 9| of the stud extends through a metallic insert 45 and a pair of nuts 5! and 552 secure it to the circuit breaker terminal 25. At the other end, the nut H and lock nut 12 complete the mounting on the panel, and nuts 13 and 15 secure it to the bus 3|.

' A washer 9"! having a perforation .Ill'II corresponding with the cross-section .ofthe. milled portion 96 of the. insulation is slipped over the milled insulating material to engage against the shoulder m2 and a washer m3 similar to washer 54 of Figure 3 and having a perforation Ifi l similar to that in washer MI is also slipped over the insulating material and brought to bear against the surface of washer Sell.

not contact the metallic portions of the stud When the stud has been thushssembled, bushing H2 of an insulating material is slip over the stud. A washer H3 is then positioned against the insulating bushing H2 and the nut "II is employed to tighten these elements. A look nut 12 when positioned completes the assembly thereof. The nuts El and i2 cooperating with washer I I3 press the bushing I 52 against the me tallic panel N35 and pull the stud so that the entire unit is held securely to the panel ltd. The flat sides 96 of the insulation the flat sides of the perforation let in the washer i3 prevent the stud as from rotating relative to the steel panel. 7

Accordingly, it may be seen that this has all the advantages described in connection with the modifications illustrated in Figures 1, 2 and 3 and has the additional advantage that a steel panel may be employee. Also as in the previous modification, axial movement may (as seen at the right hand stud 85a of Figure i) be permitted in certain of these studs by omitting the washer 87 and using a shorter bushing H2 and permitting the washer M3 to be pulled tightly against the shoulder 53 of the insulation 95.

This will provide an axial freedom of movement while precluding any rotational movement of the stud. Also, the tightening of nuts ll, 12 cannot place a strain upon the circuit breaker base or the supporting steel panel Hill.

The insulation around the stud 85 precludes possible short circuits between poles of the circuit interrupter. Thus it may be seen that in either of the modifications described, the circuit interrupters are readily removed by loosening the nuts SI and which operation does not disturb the electrical connections at the rear of the stud and behind the panel.

Similarly the insertion of a circuit breaker may be accomplished without impairing the electrical connections and without requiring that a service man go behind the panel. If an insulated socket wrench is employed, the circuit breakers may be removed when the main conductors are energized since the circuit breaker may be handled at its outermost portions during removal.

In Figure 6, I have shown a construction which corresponds somewhat to that of Figures 1 and 2 wherein the stud members which in turn support the circuit breaker are mounted on the plurality of switch board panels I2 l.

The stud itself is shown in an exploded view in Figure 7. The essential difference between the mounting arrangement of Figure '7 and that of Figure 3 lies in the additional non-rotatable washer I64a which registers with the washer I641). Otherwise the manner of arranging and mounting of the stud is essentially the same as was previously described.

Thus the stud itself comprises a cylindrical metallic member having an area milled thereon to' form flats its on either side which terminate in the shoulders 53?. The front end of the stud has extending therefrom the threaded member I43 which in cooperation with the cylindrical member 35 forms the shoulder I44.

Shoulder IM bears against the inner end of the metallic insert Hi6 and the line terminal I26 is mounted over the threaded end I43 by passing the perforation I27 thereof over the said threaded end. The line terminal is forced against the outer end of the metallic insert I 36 by the nut I5I which in turn is held securely in place by the lock nut I52.

At the opposite end, a threaded element MI extends inwardly towards the rear from the cy lindrical portion I35 of he stud. The opening I75 in the bus bar terminal i3! is placed over the threaded end iLlI against the nut 213 which is threaded onto the end It! and the terminal is locked in place by the lock nut I75.

A washer E62 surrounds the back end of the stud and has an opening I63 therein which is so shaped as to closely coincide with the flats I35 oi the milled section of the stud. This washer is drawn against the shoulders I3! at the forward end of the flats I36.

The second washer IB la also has a central opening 55m which is similarly formed so as to closely coincide with the periphery of the milled end of the stud. This washer is drawn back tightly against the washer 262 in the operative position of the mounting so that it also embraces the flats I35.

The washer He lo is provided with a pair of horizontal extensions i584; which enter into and cooperate with the slots I53 in the third washer IEQh. The extensions 166a are of a length slightly less than the thickness of the washer its?) so that they do not pass through the opposite side of the washer.

The third Washer 565?) also has a central open ing iii 'ih which is also so shaped as to closely coincide with the flats ISt of the stud. In operativ position, this washer is drawn back tightly against the washer ltda upon the milled portion of the stud. I

it will be clearly seen in Figure 7 that the slots i are adapted to receive the extensions Itfiaon washer idea. This is only for simplicity in manufacture, the only function of the slots I68 being to receive the extensions Idea. file third washer iii ib is also providedwith a pair of horizontal extensions 55611. The two extensions I666 on opposite sides of the washer It lb are arranged in a plane which is normal to the plane of the two extensions iiilia of washer I'lida.

The extensions lliiib will enter into and cooperate with the slots it! and I5! in the inner flange ibfi formed by the counterbore I5 5 in the opening I53 of the frame member I2I. The formation of the opening 153 and the counterbore' 55s in the plate l2l of Figure? is substantially similar to the formation of the opening 53 and the counterbore 5&- in the plate ZI of Figure 3. The essential difference between these two openings is that while the openings 51 and 6| inthe plate 2| of Figure 3 are designed to closely fit around the extensions 66 of the washer Gatherein, the slots .ISi and I51 are arranged to provide a loose fit for the extensions I661) of the washer IB ib of Figure 7. 1

Thus the arrangement of the washer Iii lb on the milled flats I36 of the stud and the engage- .ient of its extensions 1155b in the slots I51 and Hit or the frame member I2I will prevent rotation of the stud. The essential purpose of the modified construction of the stud of Figure '7 over that of Figure 3 to provide not only a free floating condition at the center poles-of the circuit breaker, but also to permit some freedomof movementof the studs 'in two perpendicular planes, thus assuring adequate adjustment of any misalignment of poles in the panel on which the circuit breaker is to be mounted. J .Thus, by maln'ng the slots I51 and HSI oversize so that they are much larger than the extensions I681), the washer I547) may have some freedom of movement within the counterbore i5 6. For this purpose, it is, of course, essential that the diameter of the washer I641) be somewhat less than that ofthe counterbore I54.

Likewise, by makin the slots I68 in washer ltdo somewhat over-size so that they are larger than the cross-section of extensions Ififia of washer ii da, this washer may have some freedom of movement with respect to the washer i642).

Since both washers is l-a and IMb closely engage the I35 of the stud, any movement of the stud whi h is necessary to compensate for misalignment of the mounting holes will be permitted by the slight enlargement of the slots I51, 16! and H58. 7 v The washer 569 is positioned on the threaded end I ii of? the stud in back of the washer I841). Thiswasher has an inner bore Iii! adapted to fit over the said threaded extension. The outside diameter of the washer I68 is greater than the diameter of the central bore I53 in the plate I2 I. However, it is of such diameter that it will fit easily between the extensions Ififib of the washer 541).

The length of the flats 335 is slightly less than the total thickness of the washers I62, Ma and itdb. The washer 259 will therefore provide a Ifidb and the surface of the flange I56 in the counterbore 554. It will also provide a suitable bearing for the end of the bushing hereinafter described when washer IE2 is removed.

The relationship of all of the elements thus far described to the circuit breaker and its panel is clearly shown in the left hand stud of Figure 6. In order to secure the stud assembly in the positionhereinbefore described, the washer lb? havin an inner bore adapting it to fit over the threaded end I il of the stud is slipped over the end of the stud and is placed against the back surface of the plate I 2!.

Obviously, the washer It! has a diameter sub stantially equal to that of the washer I69 and thus is of a greater diameter than the bore I53 so that it will furnish an appropriate bearing surface against the back of the plate IZI.

Nut ITI is then threaded over the end of the stud MI against the washer I51 to lock the same in place and this securement is further locked by the lock nut I 72. The nuts i1 3 and I which secure the bus bar terminal ill! in placehave already been described. Y

When the stud is in'place, it will be seen that a clamping action against the plate I2I is provided by the washers it! and I69. Washer it? bears against the back surface of the plate I2I; Washer 169 bears against the front surface of the flange able bearing between the back face of washer hections.

I55 formed .by the counterbore I54. The locking pressure is then transmitted through the washer b, ISM and IE2 to the shoulders I37 formed in the stud by the milling of the flats I36.

The circuit breaker may thus readily be secured in position. It is also clear that in order to remove the circuit breaker from the panel, it is only necessary to loosen the nuts I52 and I5I with respect to. each of the mounting studs; and likewise to replace the circuit breaker, it is=necessary only to mount the openings therein over the threaded ends I43 of the respective studs and place the locking nuts I El and I52 thereon. Since, as before pointed out, the circuit breaker casings of phenolic material or similar commercial material do not in most cases have'their surfaces particularly true. it is necessary, particularly in three pole circuit breakers, rigidly to hold the base in positien at certain stud locations and'to prevent a clamping action at other stud locations. This type of free floating condition has already been described connection with Figures 1 and a for the particular studs therein illustrated.

Similarly, provision may be made for a floating mounting of the stud in connection with the studs herein set forth in Figures 6 and '7. It should be noted that while it is important to prevent clamping action at certain stud locations to prevent breakage or distortion of the'circuit breaker casing, nevertheless even the floating studs which are used for this purpose must be in position to furnish some support for the circuit breaker casing at that particular location.

In Figure 6, on the right hand side, I have shown the arrangement of the stud of Figure 7 to provide for the free floating condition which at times becomes necessary. Here it'will'beseen that the washer i522 has been removed and a bushing I82 having an inner bore free to pass over the threaded section I -ll of the stud and an outside diameter which is less than that of the bore 53 has been placed over the end MI between the washers i5! and IE9. The length of the bushing Hi2 is such that when the nuts Ill and H2 are tightened, the washer I61 will not bear against the back-of the plate IZI and the force will be directed to'the shoulder I31 of the stud through the washer l 59, thus preventing'any ciamping action. In this way,a stud is provided which is free to move axially while-at the same time the extensions Iiifib and ififia of the washers lfi ia and id ib prevent rotation of the stud.

Y The degree of axial movement which may be permitted for the stud when the bushing I32 is in place is determined primarilyby thelength of the bushing. However, the limiting factor is that the degree ofgaxial movement should not be so great as to cause a disengagement of the extensions I66?) from the slots i5! and IBI. By this means, a construction is provided wherein not only axial movement of astud can be permitted by utilization of the bushing I82, but also it is possible whether or not the axial movement is to be permitted, nevertheless to obtain a slight movement in perpendicular. planes which are normal to the axis of the stud so that the stud may readily adjust itself should the mounting holes in the switch 'board panel and the circuit breaker be to some slight degree misaligned.

Again, the convenience in useand operation of the stud is preser'ved since the circuit breaker may be removed from or placed on the panel without requiring access to the rear circuit con- 'Iri Figures sand 9,-'I have shown a modification of my stud wherein the supporting panels or bars 22! may be of conducting material which thus permits the utilization of structurally strong members such as steel. Here again, the circuit breaker casing has exactly the same form as the circuit breaker casings of Figures 1, 2, 4 and: 6, so that the arrangement of these members need not be further described. Similarly, the circuit connections. and the securing connections obtained by the nuts at each of the outer ends of the stud are attained in the same manner as was described; in connection with the studs of the prior figures so that these require no further elaboration.

Where a steel mounting panel is used for a load bearing and current carrying stud, it becomes essential, of course, that a safe creepage distance be maintained. This is accomplished by use of an insulated stud and bushing. Referring first to Figure 9, there is here shown a metallic stud 206 having a cylindrical flange 235. The front end of the stud 260 has a threaded extension 243 which, with the cylindrical flange 235, forms the shoulder 244. The shoulder 244 when the stud is in place, bears against the inner surface of the metallic insert 246 in the manner already described while the threaded end 243 passes through this metallic insert and through the opening 22! in the terminal 226.

The circuit breaker is then securely held in place on the stud by the nut 25! and the lock nut 252. This has already been described in connection with similar reference numbers in the prior figures.

The rear end of the stud 206 likewise has an extension 24! which is threaded at its outer end but which, however, is knurled as seen particularly in the left hand stud of Figure 8 adjacent the cylindrical flange 235. This knurling is provided in order to maintain a secure bond between the metallic portion of the stud 200 and the insulating sleeve 283 which is molded thereon. The insulating sleeve 283 includes a cylindrical flange 2!!) having on the front surface the face or shoulder 2! I. The insulating sleeve also includes on the rear side of the flange 2!!! a section 2!3 having a diameter equal to the diameter of the metallic flange 235. The sleeve itself, between the flange 210 and the flange 235, is of the same diameter as flange 235. Between the section 213 of' the sleeve 283 and the flange 2!!! thereof, I provide a squared section 2I5 which is thus on. the rearward side of the flange am. As may readily be seen from an inspection of Figures 8' and 9, the section 2!3 of' the insulating sleeve 283 terminates substantially short of the end of the threaded extension 24! to form the shoulder 2 I1.

The insulating sleeve 283 which is integrated with stud200 by reason of its being molded around the knurled portion thereof, may be made of a diameter which is determined by the amount of voltage used. More specifically, the positioning and diameter of the insulating flange 210 will govern the creepage distance. I

A. Washer 264 having'the. square central open.- ing 2.65. surrounds the insulated stud, the said squared opening being made to fit closely on the squared section 215. In. operative'position, this washer willpress against the back face of. the

flange z-m. Washer 254 is provided withv a pair of horizontal extensions 266 which normally will enter into and engage the holes 25'! and 26! inthe supporting plate 22! when the: parts are as- An additional washer 266 having the square central opening 216 corresponding in size to the opening 265 in washer 264 also is fitted over the stud with the opening 2'16 closely fitting over the squared section 2I5 and the face of the washer 269 bearing against the back face of the washer 264. As may readily be seen from Figure 8, when the parts are assembled for operation, an insulating, sleeve 262' surrounds that portion of the insulated section 2|3 of the stud which projects through the rear side of the metal panel 22!.

A washer 26'! and a pair of nuts 21! and 272 press this sleeve against the back of the panel 22! and pull the flange 2l6 of the insulating sleeve of the stud tightly against the washers 264 and 266 and hence pull these members tightly' against the front of the panel 22! to hold the unit securely in the said panel. The cooperation of the squared opening of washer 264 with the squared portion 2l5 of the stud and the engagement of the extensions 266 of the washer 264 in the openings 25'! and 26! of the panel prevent the stud from rotating relative to the panel. I

The length of squared section 2H5 is such that it does not abut against panel 22!. The length of section 2! 5 is less than the summation of washers 264 and 269.

As previously pointed out, the opening 214 of bus bar terminal 2'3! is fitted over the threaded end 24! of the stud 266 and is securely held in place by the nuts 213 and 215. The position of the stud 266 for a tight clamping action is shown on the left hand side of Figure 8. Where it is necessary to permit axial movement of the stud owing to distortion or lack of trueness of the casing of the circuit breaker, then the modification shown on the right hand side of Figure 8 may be made in the mounting of the stud.

For this purpose, the washer 269 is omitted and a shorter insulating sleeve 28211 is used instead of the bushing 282. This permits the washer 26'! to be pulled tightly against the shoulder 2!! on the back surface of the insulation. Since the insulating sleeve 282a, is sufficiently short so that when the washer 26'! is pulled tightly against the shoulder 2!? it does not press the sleeve 282a against the panel 22!, the right hand stud of Figure 8 is permitted to have axial movement. The length of sleeve 282a is such, however, as not to permit sufiicient axial movement of the right hand stud of Figure 8 to cause the extensions 266 to be entirely withdrawn from the openings 25'! and 26!.

Thus, while the stud is permitted some axial movement, the axial movement is not sufficient to permit a disengagement of the members which prevent it from rotating. In this modification, as well, it will be clear that the circuit breaker may readily be mounted on or removed from the panel simply by manipulation of the nuts 25! and 252 of each of the studs.

Referring now to Figures 10 and 11, I have here shown a slightly modified form of stud which, however, does not depend upon utilization of horizontal extensions to prevent rotation, but utilizes a formation of the opening in the insulating supporting panel to obtain the same.

Here referring particularly to Figure 11, the stud 366 has a cylindrical section 335 which is straddle-milled to form the flats 336. The juncture of the. flats 336 with the main bodyof the cylindrical section 335 forms the shoulders 331, The rearward end of the stud at the ends of the flats 336 has extending therefrom a threaded eX- tension 34f. The junction between the threaded extension and the milled end of the cylindrical extension 335 forms the shoulder 3!1. The front end of the cylindrical section 335 has extending therefrom a threaded end 343 forming at its junction with the cylindrical section the shoulders 344.

The circuit breaker shown in Figure has exactly the same construction as that shown in the prior figures. Thus the shoulder 344 of the stud bears against the inner surface of the metallic insert 346 while the threaded end 343 passes therethrough and also passes through the opening 321 in the line terminal 326 and is securely held in place by the nuts 35! and 352. The opening 353 in the insulating supporting panel 32! has a shape corresponding exactly with the milled portion of the stud 330 so that the flats 335 thereof enter thereinto and are closely engaged by the inner surfaces thereof to prevent rotation of the stud 30!].

The spacing washers 369 and 361 here have central openings 31!] adapting them to fit over the milled portion of the stud. This is necessary since they are intended to pass over that portion of the stud which is milled. They do not, however, cooperate in any special way in preventing rotation of the stud, the prevention of rotation being obtained by the shaping of the opening 353 to closely engage the milled portion of the stud.

The stud is tightly positioned in place by the nuts 31! and 312 in the manner previously described and the bus bar terminal 33! is held in place over the threaded end 34! of the stud by the nuts 313 and 315. Here it will readily be seen that when the stud is held in place in the manner shown at the left hand side of Figure 10, it can have no axial movement and at the same time it is prevented from rotational movement by engagement of the milled portion thereof in the squared hole 353 of the insulating supporting panel 32!.

Should it, however, become necessary to provide for axial movement of the stud for purposes hereinbefore pointed out, then removal of the spacing washers 361 and 369 accomplish this result. When, as shown at the right hand side of Figure 10, the washers 361 and 369 are removed. then the washer 31! may be tightened directly against the shoulder 3!1 on the stud so that clamping action of the stud members against the panel 32! is prevented and the stud is permitted to have an axial movement to a degree which is determined by the amount by which the shoulder 3l1 of the stud normally extends beyond the back face of the panel 32!.

Here again it will be seen .that while axial movement is thus permitted, the engagement of the milled portion of the stud in the opening 353 of similar cross section in the panel 32! prevents rotation thereof. Thus once more even though the circuit breaker casing may be disaligned or distorted, it may nevertheless be mounted in place and certain of the studs may be given some axial movement to permit the utilization thereof atleast for positioning the slightly distorted portion of the circuit breaker casing on the panel.

Again it should be pointed out that since in a three-pole circuit breaker six such mounting studs are used, the fact that one or two or even three of the studs at various locations cannot exert a tight clamping action, but are permitted to have axial movement does not prevent the secure mounting of the circuit breaker upon the panel.

The tight clamping action which is obtained by the three or four studs which can be tightened ensures absolute securement of the circuit breaker on the panel. The one, two or three remaining studs which must of necessity be permitted axial movement nevertheless serve to position the circuit breaker with respect to the particular openings through which they pass.

Again it will be obvious that the circuit breaker may be removed from or placed on the panel simply by manipulation of the nuts 35% and 352.

In Figures 12 and 13, I have shown a slight modification of the construction of Figures 10 and 11 where again a supporting panel 42! of insulating material is used. Here instead of the broached opening 353 of Figure an opening 453 is provided in the panel. This opening is backed up by a plate 480 preferably of insulating material which is secured against the back surface of the panel 42! in any suitable manner, as,

for instance, by the self-tapping screws 48!, 48!.

The insulating plate 480 has an opening 482 therein which registers exactly with the opening 453. The opening 482 is substantially equal in its vertical diameter to the diameter of the opening 453 but the sides of the opening 482 are flat and extend substantially over the opening 453 in order to provide a suitable rotation preventing opening to engage the milled portion of the stud.

The stud 4343 consists of a cylindrical member 435 which is turned and threaded at the front end 443, thus forming the shoulder 444. The cylin drical member 435 is also turned and threaded at the rear end 44! to form the shoulder 4H and is also straddle milled to form the flats 436 communicating with the shoulders 431. Here again the shoulder 444 bears against the inner end of the metallic insert 443 in the circuit breaker and the threaded end 443 passes therethrough and also through the opening 421 in the line terminal 426 where it is secured by the nuts 45! and 452.

The cylindrical portion 435 of the stud 400 is of a diameter which permits it to pass through the openin 453 in the panel 42!. The milled portion thereof passes through the opening 482 in the plate 48!] so that the flats 435 thereof are engaged by the sides of the opening 482, thus preventing rotation of the stud.

A spacing washer 461 having an opening 410 permitting it to pass over the milled portion of the stud is then placed over the portion of the stud projecting beyond the plate 480 and the entire assembly is locked in place by the nut 41!, An additional locking washer may be used if desired.

The bus bar terminal 43! is then placed over the end 44! of the stud and held in place by the nuts 413 and 415. When all of the elements are appropriately tightened, it will be seen from an inspection of the left hand side of Figure 12 that the operation of the stud assembly is sufiiciently like those already described as not to require further description.

In order to provide for axial adjustment of the stud for the purposes already fully described, it is necessary only to remove the washer 461 which may, of course, be of any appropriate thickness to accomplish this purpose. When the washer 461 is removed, it will be seen that the nut 41! may then bear tightly against the shoulder 4 l1 of the stud without producing any clamping action against the panel 42!. Thus when the stud of l I I E i E Figure 13 is arranged in the manner shown at the right hand side of Figure 12,v it may have axial movement without however being permitted to rotate. All of the advantages of this type of construction have already been previously described and need not be further set forth.

In Figures 1a and 15 I have shown a further slight modification of my stud and particularly a further modified means for preventing rotation thereof while nevertheless permitting axial movement for alignment purposes.

The stud 500 has a metallic flange 535. A threaded extension 543 is connected to the for ward end of metallic member 535. This extension is of less diameter than the portion 535, thus producing the shoulder 544. As is seen more particularly at the left hand side of Figure 14, the rear end of stud 50B is turned down to produce the extension 515 of limited diameter which at its outer end is threaded at 54 I for purposes which will now readily be understood.

The section 515 of the metallic portion of the stud is knurled so as to receive and securely retain a molded sleeve of insulation 583. The sleeve 583 as will readily be seen from an inspection of the cross sectional view of Figure 14 is a member which is T-shaped in cross section, having the principal flange 5H] and a section 5l3 of reduced diameter, a shoulder 531 being formed by reason of this change in diameter of the sleeve.

The stud is adapted to pass through and engage in the opening 553 in the panel 521, The opening 553 is counter-bored at 554 to produce the inner flange 556. An opening 551 is also formed near the periphery of the opening 553. The side opening 551 extends into the flange 555 and is a completely enclosed opening adjacent the periphery of the opening 553 but the section thereof which extends through the counter-bore 554 is semi-circular. This may best be accomplished by first drilling the small hole 551 in the panel 52 I and then drilling the bore 553 adjacent the hole 551 without breaking the periphery of this hole.

Thereafter, the counter-bore 554 is drilled so that the periphery thereof passes substantially through the axis of the hole 551, thus producing a hole outside of the periphery of the opening 553 and a slot in the counterbore 554.

A bronze pin 566 is force-fitted into the hole 551 and extends up into the counter-bore 554 and projects thereinto, particularly as shown in Figur 14. Also as seen in Figure 14, the neck 513 of the insulated member 583 is slotted at 55l to register with the pin 555. The pin 555 does not extend beyond the forward face of the panel 521 so that it does not interfere in any way with the clamping action of the stud hereinafter described.

It will now be obvious that the engagement of a portion of the periphery of the pin 556 in the slot 551 of the insulated portion of the stud will now prevent rotation of the stud while at the same time the pin does not prevent longitudinal movement thereof. The clamping action of the panel 52| is obtained by inserting the stud so that the shoulder 531 thereof bears against the outer face of panel 52L It will here be seen that the inner end of the neck 513 will not then bear against the flange 556, thus ensuring that the clamping action will be obtained at the surface 531. A washer 551 is then placed over the threaded end 541 of the stud on the rear side of the panel.

This washer is of greater diameter than the bore 553 and thus provides a bearing surface Here again it should be noted that the line terminal 525 of th circuit breaker is secured in position over the forward end of the stud by the nuts 551 and 552 so that the circuit breaker may be placed in position or removed from the switch hoard simply by manipulation of these nuts. The

bus bar terminal 551 is held on the threaded end 551 of the stud by the nuts 513 and 515.

As may readily be seen in Figure 14, the open-- ing 555 is over-size, it being much larger in diameter than the portion 54[ of the stud which extends therethrough. This is to permit the mounting of the bushing 582 as seen in the right hand side of Figure 14 within the opening 553 when it is desired to permit the stud to have axial movement in order to avoid a clamping action on the panel 521 for reasons already fully set forth.

When it is necessary to permit the stud to slide axially then a bushing 582 is slipped over the stud between the Washer 561 and the rear face of the neck portion 513 of the insulating member on the stud. The bushing 582 is of a length which is greater than the distance between the face of the neck portion 513 and the upper face of panel 52 i when the stud is clamped tightly in position.

Owing to this increased length, when the washer 551 is tightened against the bushing 582 by the nuts 51! and 512, then the bushing is forced against the face of the neck member 513 while the washer 551 nevertheless remains clear of the rear surface of the panel 52 l Accordingly, clamping action against the panel is prevented by the interposition of the bushing 582 so that the stud on the right hand side of Figure 14 may have axial movement for all of the purposes previously set forth.

In Figures 16 and 17 I have shown a construction which is exactly similar to that of Figures 14 and 15 and which accordingly requires no further description except with respect to the slight modification of the stud to prevent rotation thereof. In this modification, the counter-bore 554 is provided with two semi-circular receses 580, 585 on opposite sides thereof, apart. The neck portion 5l3 of the stud is provided with lateral extensions 59!], 590 which are adapted to enter into and register with the extensions 580 in the counter-bore 554 thus preventing rotation of the stud while the nuts 55! and 552 are manipulated. With this single exception, the construction of Figures 16 and 17 is exactly like that of Figures 14 and 15.

Of course, it should be remembered that the essential reason for preventing rotation of the stud while it is in position in the panel is to permit the tightening of the nuts carried by the stud. Obviously if the stud were able to rotate, then no amount of rotative motion of the nuts would be effective actually to tighten the members.

In Figure 18 I have shown a slight modification of the metal insert 556 in each of the circuit breaker structures which may, if desired,-be substituted for the metal insert 45 of Figures 1, 2 and 4 or for the similar inserts in the other preceding figures. Obviously, the metallic insert 545 is mounted on and made a part of the circuit breaker itself, but must be so arranged as to cooperate with the stud construction.

In this construction, I have shown a panel 521 of a switchboard or other structural member for 17 supporting the circuit breaker, the said panel having an opening 653 through which a stud 600 passes. The stud 600 is here schematically shown, it being understood that it may have any of the forms of the various studs already described.

Metallic insert 646 is mounted in an opening 650 in the circuit breaker housing. Contrary to the inserts of the prior figures, the insert 645 of Figure 18 does not have any formation which adapts it to be secured into the molding of the circuit breaker housing. With respect to the molding, it actually is free floating in that the cross section of the opening 658 is substantially the same in area and shape as the cross section of the insert 646. The insert 646 is, however, non-circular in cross section so as to prevent rotation thereof and obviously the opening 650 is of similar non-circular cross section.

The forward or outer end of the insert is turned down to a cylindrical cross section at 603 thus forming the shoulder 604. The shoulder 604 bears against the inner surface of the line terminal 626. The cylindrical section 603 passes through the opening 62'! in the line terminal 626 and is riveted at 665 to form an electrical current carrying engagement with the circuit breaker terminal 626.

The metallic insert 646 also has a bore Hi! to permit the passage therethrough of the threaded end 643 of the circuit breaker stud 600.

In operation the shoulder 644 of the circuit breaker stud will bear against the inner face of the metallic insert. By the utilization of this type of insert, the necessity for the formation of a special ribbed metallic insert and the necessity for molding the metallic insert in the circuit breaker housing is dispensed with.

As will be seen, any strain that may occur will take place between the shoulders 63'! of the stud 60!] bearing against the panel 62| and the said shoulder 63! will act as a spacer in the mounting of the circuit breaker away from the panel. The special importance of this modification is that the strain of the clamping forces in the circuit breaker itself will not be on the molded housing of the circuit breaker but upon the flexible terminal member 626.

This is so particularly because the metallic insert 645 can slide readily with respect to the molded housing of the circuit breaker. It may well be, in fact, that by the utilization of this kind of metallic insert which is actually floatingly mounted in the circuit breaker housing itself, the necessity for the floating arrangement of the stud may be dispensed with. However, this requires a modification of the circuit breaker construction.

Assuming the rigid arrangement of the circuit breaker terminal member which occurs in most circuit breakers which are now manufactured commercially, the necessity for forming a stud which can be arranged to float axially for all of the reasons above pointed out still remains.

It might also be noted here that with the arrangement set forth in Figure 18, if the section 635 of the stud 800 which enters into the opening 650 of the circuit breaker is of the same noncircular cross-section as the opening 650 of the circuit breaker then that in itself will be enough to prevent rotation of the stud, thus dispensing with the necessity of any cooperating elements on the panel itself. This again presupposes either the existence or the manufacture of circuit breaker housings which are peculiarly suited to this type of operation.

The arrangement of the studs of Figures 1-1'7 so that they float axially is still necessary in con nection with existing types of commercial circuit breaker housings and is o f course necessary wherever the floating or resilient arrangement cannot for structural or other commercial reasonsbe incorporated in the circuit breaker housing itself.

It should be noted for instance that where reliance is placed on the flexibility or elasticity of the current carrying terminal 626 in the circuit breaker to provide for the floating condition that nevertheless when the nuts 65! and 652 are tightened against the terminal 626 and hence against the outer shoulder 604 of the metal insert no further axial movement of the stud is possible. This kind of automatic adjustment owing to the yieldability of the terminal itself within the housing and hence to the yieldability of the metallic insert 646 permits the circuit breaker housing automatically to adjust itself to irregularities without any residual floating condition in any of the studs when they are all tightened in place.

This arrangement will absorb all shocks. The circuit breaker housing may be spaced at a distance from the panel by making section 635 of the stud of a sufficient length to compensate for any irregularities in the surface of the housing.

Again it is pointed out, however, that where existing circuit breaker structures are to be mounted on a panel the floating arrangement possible by the use of the studs of Figures 1-17 becomes essential.

In the foregoing I have described a mounting stud for a circuit breaker which enables the circuit breaker readily to be removed from the front of a switchboard and readily to be remounted on the front of the switchboard without the necessity for obtaining access to the rear of the switchboard. The arrangement of the mounting studs which I have herein described also makes it possible by the addition or removal of certain members thereof, to make the stud a free floating mounting element. This is particularly useful at points where tight clamping of the circuit breaker casing to the panel would be injurious to its molded construction.

In theforegoing I have also set forth means whereby automatic adjustment of the mounting structure may be obtained by a modification in the construction of the circuit breaker housing itself.

In all of the foregoing I have described my invention only in connection with preferred embodiments which have actually been tested in practical use and found effective to perform the functions required of them. It will be obvious that many further modifications and adaptations of my invention both with respect to the struc tures of the various elements thereof and also with respect to the various uses thereof and also with respect to the various adaptations in which these mounting elements may be used should now be obvious.

Accordingly, I prefer to be bound not by the specific disclosures herein but only by the appended claim.

I claim:

In electrical switchgear, a stationary panel having a principal opening, a round conducting stud extending through said principal opening in said panel, a locking member slidable along [said stud .to a nonerotatableiposition thereon;

said panel having additional openingstherein; said locki'ngrnember havingfingers engageable in said additional openings to. prevent relative rotation therebetween;v said stud comprising a cylindrical portion and threaded portions at each endgshoulders at the junctions of said cylindrioaland said threaded portions, a pair of parallel opposed flats on one end of said cylindrical portion; shoulders normal to theaxis of ithe stud at theendsof said flats remote irom HERBERTTC. GRAVES, JR. 

